I see this message quite a bit. Sometimes straight from trying to open a project from Go Pro Omni importer. Sometimes an existing already open project crashes and when I try to re-open - I get this message.

I am working with very long clips - and the d-warp can take 12 hours. So it's not ideal when the project is corrupted.

I had this happen last night. I too am working with long clips, so I feel your "hours of processing down the drain" pain. I did not take a screen shot of the error message since I was too busy swearing. I did send a crash report, and I do remember that it had auto populated the comment box with something like "bad allocation". When I tried to reopen the kava file, it said it was corrupted. I tried with AV3 and AVP 2.6. Nothing worked.